Heteroepitaxial film crystal silicon on Al2O3 for solar cells on cube-textured metal foil

Crystal silicon is an excellent photovoltaic (PV) semiconductor: silicon is abundant, environmentally benign, capable of high solar conversion efficiencies, and profits from an unparalleled scientific knowledge base. However, the energy-intensive, inefficient and expensive processes that turn sand into a crystal silicon (c-Si) wafer account for more than half of today s Si PV module costs. Because the peak flux of solar energy on Earth is only about 1 kW/m2, large areas must be covered with inexpensive PV to provide for TW-scale electrical power needs. To circumvent the costly wafer fabrication step, it would be ideal to grow 2-20 micron thick PV-quality silicon absorber layers directly from silane gas onto inexpensive substrates at temperatures below 800 C.